The American Antiquarian Society (AAS), located in Worcester, Massachusetts, is both a learned society and national research library of pre-twentieth century American History and culture. Founded in 1812, it is the oldest historical society in the United States with a national focus. Its main building, known also as Antiquarian Hall, is a U.S. National Historic Landmark in recognition of this legacy. The mission of the AAS is to collect, preserve and make available for study all printed records of what is now known as the United States of America. This includes printed records from first European settlement through the year 1876.

The AAS offers programs for professional scholars, pre-collegiate, undergraduate and graduate students, educators, professional artists, writers, genealogists, and the general public. AAS has many digital collections available, including A New Nation Votes: American Election Returns 1788–1824.

The Library collection of the AAS contains over three million books, pamphlets, newspapers, periodicals, graphic arts materials and manuscripts as well as books from all fifty U.S. states, most of Canada and the British West Indies are included in their repository. The Society has two thirds of the books printed in the United States before 1820. Many of these volumes are exceedingly rare and many are unique. One of the more famous volumes held there is a copy of the very first book printed in America, The Bay Psalm Book. AAS claims proprietary reproduction rights to the works in its collection, even for those works that are no longer under copyright; a position which is not supported by US law. AAS also has one of the largest collections of newspapers printed in America through 1876.

The following is a quotation from the homepage of the American Antiquarian Society:

The American Antiquarian Society (AAS) is an independent research library founded in 1812 in Worcester, Massachusetts. The library's collections document the life of America's people from the colonial era through the Civil War and Reconstruction. Collections include books, pamphlets, newspapers, periodicals, broadsides, manuscripts, music, graphic arts, and local histories.